A385494 Total number of 1's in the decimal digits of the divisors of n.

1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 1, 2, 1, 2, 1, 2, 1, 3, 2, 2, 3, 2, 1, 3, 1, 2, 2, 2, 2, 3, 1, 3, 2, 1, 1, 3, 1, 2, 3, 2, 1, 2, 3, 2, 2, 1, 1, 4, 2, 2, 2, 2, 2, 3, 1, 2, 1, 3, 2, 3, 1, 1, 2, 2, 3, 2, 1, 3, 2, 2, 1, 4, 2, 1, 1, 3, 1, 4, 3, 1, 2, 1, 2, 3, 1, 2, 3, 3

Offset: 1

Author

Robert Israel, Aug 27 2025

Keywords

• nonn
• base
• new

Examples

			a(11) = 3 because of the divisors of 11, there is one 1 in 1 and two in 11.
a(60) = 4 because of the divisors of 60, there is one 1 in 1, one in 10, one in 12, one in 15 and none in the other divisors.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A093653, A387357.

Programs

Maple

f:= proc(n) local d; add(numboccur(1, convert(d,base,10)),d=numtheory:-divisors(n)) end proc:
map(f, [$1..100]);

Mathematica

a[n_]:=Count[IntegerDigits[Divisors[n]]//Flatten,1]; Array[a,100] (* Stefano Spezia, Aug 28 2025 *)

PARI

a(n) = sumdiv(n, d, #select(x->(x==1), digits(d))); \\ Michel Marcus, Aug 28 2025

Python

from sympy import divisors
def a(n): return sum(str(d).count("1") for d in divisors(n, generator=True))
print([a(n) for n in range(1, 101)]) # Michael S. Branicky, Aug 27 2025